Hitherto, there is a thermal printer which performs printing using a thermal head. The thermal head is a so-called line thermal head in which a number of heating elements are formed on a substrate to be arranged in a row, and is provided so that the arrangement direction of the heating elements is perpendicular to a sheet transport direction.
A platen roller is disposed to oppose the thermal head, and the thermal head is biased against and comes into pressure contact with the platen roller. A sheet transport path on which sheets are transported is formed between the thermal head and the platen roller.
The sheet is transported as the platen roller rotates while being guided by a guide plate and is printed by the thermal head. For example, Patent Literature 1 discloses that a sheet is guided by a guide inclination plate, a pair of width restriction plates, and a printing surface pressing plate provided in the width restriction plate.